The proposed research has as its goals the production of primate models for human psychopathological conditions. The focus is on depression and the study of the underlying neurobiological mechanisms, especially neuroendocrine parameters. Two broad categories of techniques will be used to produce depressive like syndromes in rhesus monkeys - specific brain site injections with 6 hydroxydopamine and experimental separation of monkeys which have become attached to each other. Systematic studies of the interaction of these two kinds of manipulations will be an area of special interest since it is difficult in humans to obtain data on how biogenic amine systems interact with social events such as separation. Also, the research will include rehabilitative studies with a special focus on the reversal of either socially or pharmacologically induced depressive syndromes by pharmacotherapies or electroconvulsive therapy.